I just got in a replacement EBCM module for my 99 FRC @ the tune of $1400. Plugged her in and getting the same code as my old box C1225. I've ohm ed the speed sensor and it checked good per the manual @ 1120 ohms, I've even replaced the 18" connector wire with a new one. We hooked a Solus scanner to the car and watched both front wheel speed sensors track evenly with no sign of there being a problem. The man I got the new box from declares its good. Just wondering if there is anybody nearby out there that would consider installing it in their car to verify its operation. I know that's asking a lot. Thanks

 

What tires/wheels are you running?

 

sounds like too much coincidence to me also. I've checked the wiring, give me some suggestions where to start over. Thanks

 

If you can see all 4 wheel rpm's on a scanner that at least says your wiring is OK. Sensor may not be reading right or your tire diameters are not correct. I have not watched mine on my scanner but with different stock wheel sizes, the fronts should be 1 rpm and the rears a different rpm. What are you seeing on the scanner?

 

we could only watched the fronts they matched exactly, these tires and wheels have been on the car for over a year and just developed a problem 17's on the front and 18's on the back.

 

You have to measure the diameters of the tires not the rim sizes. There should be a 1/2" to 1.5" difference in the diameters with the rears being more.

 

Here is what it takes to set a c1225
C1225 through C1228
The EBCM detects a rapid variation in the wheel speed. The wheel speed changes by 16 km/h (10 mph)or more in 0.01 second. The change must occur 3 times with no more than 0.2 seconds between occurrences.
Most likely you have an intermittent open or short in the ss circuit causing the wheel speed signal to drop out. As stated above, check the connector. If it's ok, you can swap the front hubs and see if you still have the c1225 or it moves to the other side. If not you have a problem in the harness to the left front wheel. A replacement harness repair kit should be available from the dealer. It replaces the part that's routed threw the suspension. Just splice it in.

 

Check the female pins at both ends of the harness. They get saggy.

 

Ok, I almost gave up on this repair, I followed the service manual step by step with no resolution to this problem. I ohm ed through the pickup as instructed and got 1109 ohms which is within specs by the manual. I replaced the jumper harness with a brand new one, I bought a replacement ECBM module which was the last step in the manual to remove the C1225 code I was getting. In the end I bought a used bearing assembly from a 40,000 mile rear end wrecked car ($40). I ohm ed it out before I installed it, it checked very close to my original unit @ 1125 ohms. This was my last resort, (and I wasn't very confident this would change anything) other than to figure I had 2 bad modules that threw the same code (unlikely). Installed the replacement bearing assembly yesterday and drove the car ~ 10 miles and got no warning lights at all, thank god. My next step is to put my original ECBM module back on and confirm it wasn't bad in the first place. There is a lot of information in the service manuals, but in my case it didn't help find my problem. Thanks for all of the suggestions I received, I hope this post helps someone else not have go through the process I did. One last thing after I verify my original ECBM is good I know where there is a good V one that can be bought. I think The guy I bought it from will take it back, he's been good to deal with so far.